How to Open the Secured WinForms PDF File in C#, VB.NET?

Secured PDF file requires a password to open, edit, or remove the restricted operation. Syncfusion Essential® PDF is a .NET PDF Library used to create, read, and edit PDF documents. Using this library, you can open a secured PDF file using a password in C# and VB.NET with our WinForms PDF feature tour page.

Steps to open a secured PDF programmatically:

1. Create a new C# console application project.
2. Install the Syncfusion.Pdf.WinForms NuGet package as a reference to your .NET Framework application from NuGet.org.
3. Include the following namespace in the Program.cs file.

C#

using Syncfusion.Pdf.Parsing;
using Syncfusion.Pdf.Security;

VB.NET

Imports Syncfusion.Pdf.Parsing
Imports Syncfusion.Pdf.Security

4. Use the following code snippet to open a secured PDF file.

C#

// Load the password-protected PDF document
PdfLoadedDocument loadedDocument = new PdfLoadedDocument("SecuredPDF.pdf", "password");
// Change the permission
loadedDocument.Security.Permissions = PdfPermissionsFlags.CopyContent | PdfPermissionsFlags.AssembleDocument;
// Save the PDF document
loadedDocument.Save("Security.pdf");
// Close the document
loadedDocument.Close(true);
// This will open the PDF file, so the result will be seen in the default PDF viewer
Process.Start("Security.pdf");

VB.NET

' Load the password-protected PDF document
Dim loadedDocument As New PdfLoadedDocument("SecuredPDF.pdf", "password")
' Change the permission
loadedDocument.Security.Permissions = PdfPermissionsFlags.CopyContent Or PdfPermissionsFlags.AssembleDocument
' Save the PDF document
loadedDocument.Save("Security.pdf")
' Close the document
loadedDocument.Close(True)
' This will open the PDF file, so the result will be seen in the default PDF viewer
Process.Start("Security.pdf")

You can download the work sample from PDFSecuritySample.Zip.

By executing the program, you will get the PDF document’s security settings as follows.

Take a moment to peruse the documentation, where you will find other options like opening a corrupted PDF document, opening an existing document from a stream, opening an existing document from a byte array, saving a PDF document to a stream, saving a PDF document to the same file or stream and features like encrypt PDF document, and adding a digital signature to the PDF document with code examples.

Refer here to explore the rich set of Syncfusion Essential® PDF features.

An online sample link to encrypt the PDF document.